From: Scott Morris (smorris@ipexpert.com)
Date: Wed Aug 22 2007 - 11:20:28 ART
Flood reduction on a demand circuit would be redundant. That's one of the
features of demand circuit. (RFC 1793 if you're bored)
Demand circuit is also used for hello suppression between two neighbors, to
make things quieter.
So both methods reduce the overall traffic flow on a link, just approach it
differently based on the link-type. Knowing the details of both should help
you make the correct decision if faced with it in the lab!
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
_____
From: Shamin [mailto:ccie.xpert@gmail.com]
Sent: Wednesday, August 22, 2007 10:14 AM
To: smorris@ipexpert.com
Cc: subodh.rawat@wipro.com; reto_ccie@yahoo.com; ccielab@groupstudy.com
Subject: Re: IP ospf demand-circuit V/S IP ospf flood reduction ???
Scott,
Thank you for your clarification.
If you can clarify my original concern ,i will be grateful i.e when to use
" ip ospf demand-circuit " v/s " ip ospf flood reduction".
I know that, demand-circuit is used over p-t-p networks. But is the
functionality of the two commands the same when it comes
to reducing the LSA refresh. Furthermore, can " ip ospf flood reduction
command " be used on a demand circuit,
Thanks in advance
Regards
Shamin
On 8/22/07, Scott Morris <smorris@ipexpert.com> wrote:
Per Appendix B of RFC 2328:
"LSRefreshTime
The maximum time between distinct originations of any particular
LSA. If the LS age field of one of the router's self-originated
LSAs reaches the value LSRefreshTime, a new instance of the LSA
is originated, even though the contents of the LSA (apart from
the LSA header) will be the same. The value of LSRefreshTime is
set to 30 minutes."
"MaxAge
The maximum age that an LSA can attain. When an LSA's LS age
field reaches MaxAge, it is reflooded in an attempt to flush the
LSA from the routing domain (See Section 14). LSAs of age MaxAge
are not used in the routing table calculation. The value of
MaxAge is set to 1 hour."
The re-flooding occurs at half of maxage (30 minutes).
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com <mailto:smorris@ipexpert.com>
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com <mailto:nobody@groupstudy.com>
[mailto:nobody@groupstudy.com] On Behalf Of
subodh.rawat@wipro.com
Sent: Wednesday, August 22, 2007 4:39 AM
To: reto_ccie@yahoo.com; ccie.xpert@gmail.com; ccielab@groupstudy.com
Subject: RE: IP ospf demand-circuit V/S IP ospf flood reduction ???
Just to correct you: This refreshment of LSA takes place after 1 hour not 30
minutes.
Subodh
-----Original Message-----
From: nobody@groupstudy.com [mailto: nobody@groupstudy.com] On Behalf Of
eicc
tester
Sent: Wednesday, August 22, 2007 4:38 AM
To: Shamin; Cisco certification
Subject: Re: IP ospf demand-circuit V/S IP ospf flood reduction ???
Hi
"ip ospf flood reduction" just avoid the refreshement of LSA every 30
minutes.
"ip ospf demand circuit" mean that a link which is under an OSPF area ,
don,t send OSPF hello packet all the time. This avoid the fact of bring the
circuit (probaly and dial or isdn) just for sent hello packet periodically,
the neigbhor relations is still maintaned.
Shamin <ccie.xpert@gmail.com> wrote:
Hi All,
Can any one tell me , when the commands "ip ospf flood reduction" is used
over " ip ospf demand circuit" .
I know that, "Ip ospf demand circuit is used in point to point connections.
Does that mean, ip ospf flood reduction"
is used in Broadcast and NBMA OSPF networks. I am bit confused as to which
command to apply in a particular scenario, mainly if the question asks to
reduce the "paranoid updates" in ospf that occurs every 30mins.
Thanks in advance.
Regards
Shamin
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